How can I simplify the formula in R? - r

Question

I want to estimate a set formulas in R by systemfit,for each formula,it's mathmatic expression can be written as
https://www.mathcha.io/editor/VQKXXuLvCjWClxjyy4Ie0xBKOC1eN3lgCMMXdgG
In stata ,I can handle it by
gen double `lnap' = `a0' + `a1'*`lnp1' + `a2'*`lnp2' + `a3'*`lnp3' + `a4'*`lnp4' + `a5'*`lnp5' + `a6'*`lnp6'
forvalues i = 1/6 {
forvalues j = 1/6 {
replace `lnap' = `lnpindex' + 0.5*`g`i'`j''*`lnp`i''*`lnp`j''
}
}
gen double `bp' = 0
forvalues i = 1/6 {
replace `bp' = `bofp' + `lnp`i''*`b`i''
}
replace `w1' = (`a1' + `g11'*`lnp1' + `g12'*`lnp2' + `g13'*`lnp3' + `g14'*`lnp4' + `g15'*`lnp5' + `g16'*`lnp6' + ///
`b1'*(`lnm' - `lnap') + `l1'/`bp'*(`lnm' - `lnap')^2 + `z1'*`eta11' + `z2'*`eta21' + `z3'*`eta31' + `z4'*`eta41'+ `z5'*`eta51'
I have read manuel for formula,it seems that the only way is to simplify this equation.I wonder if you can tell me how to write this complex equation to formula in R?
Many thanks!